Feeling Worse After B12 Injection? - Pernicious Anaemi...

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Feeling Worse After B12 Injection?


Hi, so I have received my 6 shots of B12. It’s the one that begins with an H (I can’t spell it). My B12 Levels were at 172, and the doctors kept insisting that it was my diet that was causing this (baring in mind I eat meat and everything fortified with B12). So I was wondering if there’s any conditions that may affect this?

Also, after 4/5 days receiving the first of my shots, I started getting more numbness and tingling in my hands and feet, and it’s progressively turned into having pains In my hands on and off (sometimes sharp stabbing pains). I am still tired (I take iron tablets 3 times a day). I’ve also experienced prolonged pains in my upper left part of my stomach, which happens every so often. I’ve also noticed that I am more sensitive to the cold and heat, ( so I may be freezing cold but to others they’re warm/ if I get Into a warm bath it’s too hot). I’m a lot more out of breath and experiencing dizziness. Lastly, I’ve been waking up from having leg cramps and my feet feel like they’re wanting to cramp constantly.

I’ve been to the doctors about the see symptoms and I need to have another blood test. I’m just worried that these symptoms may be because of the injections or something serious.

Advice please, many thanks!!

23 Replies
clivealiveForum Support

Hi Quinny99 It is not uncommon for some symptoms to appear to get worse before they get better as the B12 you are having starts repairing the damage done to your nervous system and your brain starts getting multiple messages from part of the body it had "forgotten about" or lost contact with.

I sometimes liken it to a badly tuned radio on which you have turned the volume up high trying to catch the programme you want when all of a sudden the signal comes in loud and clear and the blast nearly deafens you.

A lot will depend on the severity and longevity of your B12 deficiency as to how long before there is no further improvement or recovery.

Some symptoms will "disappear" quite quickly whereas others may take months or even years. There is no set timescale as we are all different.

It is also important that your Folate level is monitored as this is essential to process the B12.

There is a complex interaction between folic acid, vitamin B12 and iron. A deficiency of one may be "masked" by excess of another so the three must always be in balance.

Symptoms of a folate deficiency can include:

symptoms related to anaemia

reduced sense of taste


numbness and tingling in the feet and hands

muscle weakness


Folic acid works closely with vitamin B12 in making red blood cells and helps iron function properly in the body and your B12 levels were below the bottom of the range.

Initially, replacing B12 will lead to a huge increase in the production of blood cells and platelets (which occurs in the bone marrow) and can lead to rapid depletion of folate and iron stores; this can then limit the expected recovery of Haemoglobin.

Both iron and folate may be needed so please have these levels checked by your doctor.

Anyone at any age, can become B12 deficient. However, certain people are at an elevated risk. They include the following:

Vegetarians, vegans and people eating macrobiotic diets.

People aged sixty and over

People who’ve undergone any gastric and/or intestinal surgery, including bariatric surgery for weight loss purposes (Gastric bypass).

People who regularly use proton-pump- inhibitors. H2 blockers, antacids, Metformin, and related diabetes drugs, or other medications, or infections such as h-pylori that can interfere with B12 absorption.

People who undergo surgeries or dental procedures involving nitrous oxide, or who use the drug recreationally.

People with a history of eating disorders (anorexia or bulimia).

People with a history of alcoholism.

People with a family history of pernicious anaemia.

People diagnosed with anaemia (including iron deficiency anaemia, sickle cell anaemia and thalassaemia).

People with Crohn’s disease, irritable bowel syndrome, gluten enteropathy (celiac disease), or any other disease that cause malabsorption of nutrients.

People with autoimmune disorders (especially thyroid disorders such as Hashimoto’s thyroiditis and Grave’s disease) Type 1 diabetes, vitiligo, lupus, Addison’s disease, ulcerative colitis, infertility, acquired agammaglobulinemia, or a family history of these disorders.

Women with a history of infertility or multiple miscarriages.

You appear to have "ruled out" the top line but do you "see yourself" among any of the other people?

If the cause isn't dietary then it is an absorption problem so you need to find another way of replenishing B12 initially. Most absorption problems aren't treatable but a few are - notably h pylori infection - which would mean that once that has been dealt with you would be able to absorb B12 from your diet so wouldn't need maintenance shots for life.

I am not a medically trained person but I've had Pernicious Anaemia (a form of B12 deficiency) for more than 46 years.

I wish you well.

Quinny99 in reply to clivealive

Thank you for all the information. The only thing I can say is that my mum and nan both have anaemia, but I think it’s my ferritin levels that are low (they’re at 9) and that’s why I have to take 3 iron tablets a day. I don’t think my actual iron levels are low and the doctor said that I am not anaemic. So my guess it’s to do with my stomach? But I won’t know until I get the blood test.

Many thanks!!

Milley2 in reply to clivealive

If the b12 FERRITEN folate needs to be in balance us FERRITEN 40 to low ?

Had b12 low was on injections and had h pylori

That’s being treated folate level is ok

So I’m still not well thinking I may need iron ?


I’m experiencing exactly the same as you. I had my 6 shots plus one other (last shot 1 week ago). I have a day where I feel ok and then a day where everything seems to start up again. Also my stomach that I had thought was much better before the injections is really playing up again. I’m hoping that this is due to the B12 ‘healing process’ too. I’ve decided to get my potassium, folate and iron levels checked asap, but if they are ok to just rest lots and give my body a chance to recover. I thought I would feel better straight away, but I suspect I’ve been low for years, and so it make sense that recovery might take time!

I’d be interested to know how you get on. I’ll let you know my progress too. It’s difficult to feel ok with what is happening, if you don’t know others that have had similar experiences.

Av42 in reply to natcap1

After having the loading doses just over a year ago , I thought the doctor had got it completely wrong and they were trying to kill me . After a few weeks I felt ok but not completely myself and resigned mystic the fact this was better than nothing and would be almost myself forever . After six months I was completely myself again and live very well on three monthly injections. I was on prescribed folate but when that finished I now take a multi vitamin every day . I know I’m lucky to feel like this but there is hope you’ll get back to normal too . Good luck . Symptoms I had after loading were spots everywhere , dizziness, nausea and fogginess in head which were all more extreme than before loading.

Quinny99 in reply to natcap1

Thank you so much!! It’s quite scary this whole b12 thing. It had literally come from nowhere. For someone who hates needles this has become a difficult thing to adjust to. I will update and let you know how I get on.

Me too, feeling even worse than before the injections. Extreme muscle pains, tingling, tinnitus, dizziness, fatigue, twitching, cramps, actually often feel like I have the flu but no fever. I'm injections for 2 months now, my GP and GI still refuse to run my blood test saying it is not needed :( The more injections I get (I started injecting myself every 48 hours 500 mcg hydroxycobalamin because 1000 mcg was unbearable to deal with feeling sick for days) the more pain and symptoms increase.

I have B6 toxicity, P.A. and MTHFR C677T but GP and GI don't know anything about this and won't test my blood on folate, iron, magnesium, potassium, homocysteine, MMA or even my vits. Eating bananas and trying a very healthy diet but the increase of symptoms and pain make me very, very insecure and scared. So I will follow Ur story and send U a big hug as I fully understand how U feel x

Quinny99 in reply to PearlH

Thank you so much!! I’m just hoping that these symptoms will get better. It’s a pain being in pain all the time! It just seems that the doctor doesn’t take all of this seriously or thinks that I am making all of it up. But everyone reacts to everything differently. I hope you get the answers you’re looking for too!

PearlH in reply to Quinny99

I know...we are left in the dark :( Docs don't care (maybe a few do, but in generally they don't) as they are not educated well enough to understand what impact this has on patients. It's truly huge agony, all the pain, the neurological symptoms, the brain fog, tingling, headaches, fatigue and so on...reading stories here do reassure me though that is due to the healing process, so we must keep the faith...Feeling scared and insecure about the symptoms bothers me the most, because docs say it is highly unusual to feel the way I do :/ But like I said, they often don't care and not aware of what is really going on. So all the advice and info we can read here helps to deal with the agony...

Quinny99 in reply to PearlH

That is true that many doctors aren’t well educated about this. I’ve been to a few and none of them can tell me anything. I only got a breakthrough with this one doctor who said that I needed a blood test. If it’s none of the things he’s testing, he said it’s probably anxiety. Which it could be that’s making all of the physical symptoms happen. But I don’t think it is anxiety. I don’t know. It’s tough.

Zantegirl in reply to Quinny99

Hi Quinny99

I’m new to this site

Diagnosis with PA a month ago & had my 6 loading injections last one last week

Feel awful too , worse 😭 my b12 was 150 & serum iron 8

Spots have s

Also now started, really hope things improve soon

How are you feeling now? X x

Quinny99 in reply to Zantegirl

Since after having my 6 B12 doses, the first month of having them, I went back to the doctors because of feelings so rubbish, and it seemed like they blamed everything on my anxiety and sent me off for a blood test anyway. The second month I could tell things were improving. I could go out jogging and I felt great. Then after about two weeks I got a cold then I was back to how I was. So I’m about to go for my first injection (as I have them once every 3 months). But I’m just not well all the time, constantly in pain. I’m just hoping that this injection will make me better. I still haven’t found out my blood test results where I have been so busy. It’s supposed to check my calcium levels, iron levels, and to see if there’s any inflammation in my stomach +other things. But I haven’t had a diagnosis of anything yet, and they’re still insisting it’s my diet, when I 100% know it’s not.

I hope this helps.

Lorna12345 in reply to Quinny99

Can you please describe your pain?where is it? Character (stabbing,burning,very deep??)?how often?

Hi quinny99

I too experienced this, despite my gp telling me I would feel like a new woman after a few shots I felt worse. I suffered extreme fatigue, tingling lips, fingers and just a general lack of lust for life. It does get better, just make sure you get the next 2 or 3 monthly top up jabs...I've had to pay privately for mine as nhs seem to think a reading of 305 is ok...when it's defiantly not.

Good luck and I wish you well on your recovery xxx

Quinny99 in reply to VMITCHELL78

Thank you!!

Hi Quinny99 I was wondering if you felt any better since your last post. It’s interesting how many people do not instantly feel better from the B12 loading doses.

Quinny99 in reply to natcap1

Hi sorry, I’m going to go for my first jab since the 6 lots of jabs. After the jabs I had like one month where I felt great, like I could go out running and I’d be fine. Then I got a cold and I haven’t been the same since. I just feel like rubbish all the time and I don’t know what to do.

natcap1 in reply to Quinny99

No problem, I just came across your reply. Hang in there it will get better. I just had my first shot after the loading doses three days ago. This time I felt anxious for about 10 mins that evening, tired and achy the next day, but that has been it. A very different experience to the loading doses. I’m feeling almost normal again energy wise. Tingling and numbness has gone. So I’m sure you will get there. I haven’t attempted to get back to running or cycling yet, to let my body recover a bit. But I feel like I could try it in the next couple of weeks.

Sadly my much improved digestion has gone downhill again. So am still not feeling great and was hoping the B12 would improve it. Can’t have everything I suppose!

Quinny99 in reply to natcap1

I just don’t know what to do that will improve my health. I can’t do much until I have some sort of diagnosis so I can sort myself out. It’s frustrating when no doctors can pinpoint on what the issues are. Anyways, I hope you get better!!

natcap1 in reply to Quinny99

I do hope you get to the bottom of this. If you get the blood results I’m sure that will help. You could be low in iron now. It might explain why you felt better at first and then feel unwell again. It can also cause anxiety, along with the low B12. Folate could be a problem too. I’m just getting up to speed on what needs doing e.g. getting the levels of iron and folate checked. But a cooperative GP is what you need. It’s good you are getting the B12 and take heart that it seems common to feel worse before you get better.

If you have Pernicious Aneamia then it is possible you have other autoimmune conditions, for instance Hashimoto’s (where the immune system attack’s the thyroid), type 1 diabetes, Sjogren’s Syndrome etc. Depending on symptoms your GP should test for these too.

I hope you start to feel better soon.

Quinny99 in reply to natcap1

Thank you so much. I just need to sort myself out as it’s stopping me from going to University lectures and stuff like that. Like it needs to be sorted because it’s affecting my everyday life.

I hope you get better too.

How are you feeling now? I'm on loading injections and feeling worse

Hi how are you feeling now.. just reading all these threads and it sounds like what I'm going through now

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